Positive displacement piston pump



Feb. 9, 1965 H. E. PINKERTON POSITIVE DISPLACEMENT PISTON PUMP 3Sheets-Sheet 1 Filed Jan. 23, 1965 INVENTOR. HARRY P/N/(EE'TON ATTORNEYSFeb. 9, 1965 H. E. PINKERTON POSITIVE DISPLACEMENT PISTON PUMP 3Sheets-Sheet 2 Filed Jan. 23, 1963 INVENTOR. HA RE) E. P/NKEKTO/V fia/EM Maw 1965 H. E. PINKERTON 3,168,872

POSITIVE DISPLACEMENT PISTONPUMP Filed Jan. 23, 1963 3 Sheets-Sheet 3 F/6'. /4 F 6. l5 Jag 58a 52b 58b 46b 56a 56a 52a 52a /60 we /56 ms 30 beexposed to the chamber on the piston upstroke.

United States Patent 3,168,872 POSITIVE DISPLACEMENT PITON ?UMP Harry E.Pinkerton, R0. Box 387, Mill Neck, N.Y. Filed Jan. 23,19e3, Ser. No.253,475

' 13 (Eiaims. (Cl. 103-157) Heretofore, a composite of gear, piston andvariable .1

vane pumps have been proposed in a variety of forms, including theclassical swash plate and wobble plate pumps, slide block pumps as wellas others. However, because of their complex nature, such pumps havetypically been susceptible to only a limited number of applicationswhere clean filtered hydraulic fluid being pumped bathes all workingparts for essential lubrication, heat transfer and shock cushioning.These pumps. are, therefore, rarely applied to routine product handlingin the food, chemical and processing industries. In these cases,eithergear, piston, or vane pumps are commonly employed in a number ofvarieties exemplified by the pumps commercially available today.Unfortunately, these pumps are either not reversible or variable indisplacement to mention a few disadvantages. There is also the usualrequirement for inlet or outlet check valves which ordinarily detractfrom the accuracy, longlife and ultimate pump properties andcharacteristics.

The present invention has, for one of its principal objects, a pumpincorporating the optimum and salient features of such prior art pumpswithout concern withthe enumerated disadvantages by providing avalveless, positive displacement, piston pump capable of producingstepless variable and reversible fluid flow. 1

Another object is to provide a simple positive displacement pump havinga rotating and reciprocating ducted pistonand possessing only one movingpart, notably the piston, in the pumpfluid stream with valves, pintles,throttles, bearings, springs and other such components beingunnecessary.

A further object is to provide a pump of this nature wherein completehandling of substantially any fluid including hydraulic fluid ispossible particularly where control of flow rate and/or direction is ofimportance by the mere proper selection of only two component materials,namely that of the piston and cylinder.

A still further object is to provide such a pump with design simplicityand versatility for a wide number of applications where flow directivityand control of flow rate from zero to maximum in either direction isdesired particularly from a constant speed, uni-directional powersource. 7

Still another object is to provide such a pump for applications wheresystem costs, variable flow, valve-problems, pumping eificiency, flowreversal or gland leakage are significant factors.

A pump incorporating the teachings of the present invention employs aducted piston which reciprocates and rotates synchronously in abi-ported'cylinder. The piston duct is so arranged as to connect theports alternately with the pumping chamber. Under such circumstances,one port will communicate with the pumping chamber on the down stroke ofthe piston whereas the other port will Reversal of duct timing resultsinreversal of flow direction. Essentially, at least three cylinder-pistonarrangements are contemplated for establishing the foundationfor pumpversatility thereby covering a majority of modern day fluid handlingrequirements. Each arrangement lends it- "Ice self advantageously togland scavenging whereby piston and gland bypass fluids can be returnedat negative pressure to .the suction side of the pump system or directlyto the fluid source at atmospheric pressure. Thus, gland leakageproblems are effectively eliminated. Multiple units in monophase ormultiphase relationships are also contemplated for providing a widevariety of output characteristics ranging from the typical pulse andsuck mode of valve type piston pumps to substantially constant flow. Itshould be understood that all models are valveless and variable; and allcan be arranged in uni-directional or reversible flow. As will beexplained in detail, the three basic cylinder-piston arrangements are,respectively, termed monoplex, double monoplex and duplex.

In one embodiment of this invention, a piston-cylinder assembly iscoupled with the output of a drive motor through an interposed collar oryoke. The piston includes at its outer end a laterally projecting armhaving a ball hearing which is adapted to ride in a socket in the collarto thereby provide a universal joint between these parts. A cylinderconveniently receives the piston and is mounted on a bracket rotatableabout a vertical axis. The cylinder is provided with at least one pairof ports both of which communicate with the cylinder pumping chamber.

When the axis of the collar and that of the piston and cylinder aresubstantially coaxial, the piston does not reciprocate in the'cylinderduring rotation of thecollar. Under such circumstances, no pumpingaction takes place. When the cylinder is rotated about its pivot, thepiston will rotate at a corresponding amount relative to the collar. Thedirection of rotation, that is either clockwise or counterclockwise,determines the direction of feed. The magnitude of rotational movementdetermines the amplitude of piston stroke and, consequenty, flow rate.

In another embodiment, contemplatedby this invention, the yoke ratherthan the cylinder is pivotal. Under these circumstances, the outer endof the piston includes a collar having a splined connection with theoutput shaft of the drive motor. Thus, when the yoke is pivoted in onedirection or the other, an eccentric elliptical path of travel of theball in the yoke socket is induced, with the reciprocating movement ofthe piston at its coupling with the output shaft being compensated forby the splined connections. It should be understood in passing thatother connections between the piston and motor drive are contemplated inproviding the valveless,

reversible and variable pump of this invention and such are embraced bythe protection afforded herein.

Other objects and advantages will become apparent from the followingdetailed description which is to be taken in conjunction with theaccompanying drawings illustrating preferred as well as exemplaryembodiments of this invention and in which:

FIG. 1 shows a basic monoplex pump coupled with the output shaft of adrive motor with certain parts broken away and removed and sectioned;

FIG. 2 is an enlarged fragmentary top plan view of this pump withcertain parts broken away and removed and sectioned;

FIG. 3 is a similar ,view with the pump adjusted to provide reversefluid flow;

FIG. 4 is an enlarged fragmentary cross sectional view taken along theline 44 of FIG. 2;

FIGS. 5 to 8 are fragmentary perspective views par tially sectionedshowing the sequence of operation of the pump of'FIG. 2 and the stepstransgressed by the piston during the pumping cycle;

FIGS. 9 to 12 are similar views showing the sequence of operation of thepump of FIG. 3;

FIG. 13 is a diagrammatic fragmentary view of a basic monoplex pumpillustrated in the preceding figures;

FIG. 14"is a similar view of a basic double monoplex FIG. 15 shows abasic duplex pump;

FIG. 16 shows a scavenger monopl-ex pump;

'FIG. =17 shows a scavenger double monoplex pump;

FIG. 18 shows a scavenger duplex pump;

FIG; 19 shows a multiple monoplex pump; 7

FIG. 20 shows a multiple double monoplex pump;

FIG. 21 shows a multiple duplex pump;

FIG. 22 is a fragmentary perspective view with cer tain part designatedwith phantom lines of another embodiment of pump of this invention; and

FIG. 23 is a longitudinal sectional "view of this pump.

Refer now to FIGURE 1, a positive displacement piston pump 39 thisinvention is shown coupled with the output of a drive motor 32, both ofwhich are mounted on the platform support 34. Naturally, the supportwill vary'depending upon the selected pump application. The motor issecured to the support by mean of the suitably anchored motor bracket36. The pump 39, on the other hand, is provided with an angle bracket3%, leg 4% of which rests on the support 34 and is coupled thereto bymeans of the pivot pin =42. The bracket leg 44 has suitably securedthereto the open end of the cylinder 46. Piston '48 extends through bore50 provided in the bracket arm 44 into the interior of the cylinder.

The inner end of the piston 48 is provided with a cutout or recessedportion 52 functioning as a duct which together with the cylinderinterior at thehead of the 'piston, cooperates in forming the cylinderpumping chamber 54, The cylinder is provided with ports, 56 and 58 (seeFIGS. 2 and 3) adapted to perform as both inlet and outlet ports andcommunicate with the pump chamber 54. Tubing may be suitably coupledwith these ports as part of the circuit or systemior fluid to be pumped.

As 'will be'readily appreciated, the forward end of the piston 48 isadapted to close off or seal each port depending upon the extent ofrelative rotation of the piston in the cylinder. On the other hand, theduct 52 is adapted to simultaneously expose the pumping chamber 54 tothe other port to permit free passage into the chamber of the pumpiiuid. The piston head operates toshear the fluid on the suction strokeas it rotates in the 'path past the ports. No suction check valve isneeded since outlet pressure is never felt at theinlet port. Similarly,the outlet port is never open to the inlet, therefor, a discharge checkis not necessary. The pumping cycle and sequence of operation of thepump will be explored in detail shortly.

The outer end of the piston 48 has secured thereto a laterallyprojecting drive pin or arm 57. A ball 59 is securedto the outerterminal end of this arm 57 and forms part of a universal ball andsocket joint. In this connection, 'a collar or yoke 69 mounts the socketpart 62 of .this joint. A reduced boss 54 extends concentrically fromthe collar fitland is adapted to be keyed to the motor output shaft 66.

When the yoke lliis disposedin a substantially coaxial relationship withrespect to the piston 48 in a manner substantially designated by FIG. 1,the piston will have no stroke nor will it reciprocate upon energizationof the motor 32 and, consequently, rotation of output shaft66 and theyoke 60. Under such circumstances, no pumping action takes place. Whenthe'cylinder is pivoted about its pivot pin 42 which, incidentally, isaligned with the vertically extending axis of the yoke 60 in acounterclockwise direction, as viewed'in FIG. 2, the piston 48 will bepivoted a corresponding amount. Assumingthe depicted rotation of themotor output shaft 65, the elliptical path of travel of the ball 59 andinduced reciprocation of the piston 48 will cause the pumping fluid tobe pumped out fromthe pumping chamber 54through the port 58. In thisconnection,the port 56 will function as the inlet port; Pivoti'ng of thecylinder 46 in a clockwise direction, as shown in FIG. 3, will reversefluid flow.

7 upon the degree of pivoting of the cylinder.

The magnitude of pivotal movement of the cylinder will determine theamplitude of piston stroke and, consequently, the rate of fluid flow.

The cycle of operation of the pump 30, when disposed in the mannerillustrated in FIG. 2, is shown clearly in FIGS. S'through 8. Thus, inFIG. 5 as in FIG.'2, the piston will be at the end of its retraction orbackstroke at which the pump chamber 54 is in communication with theoutlet port'58 with the inlet port 56 sealed by the head of the piston48. The continuously rotating piston will then be forced for-wardlyintothe cylinder '46 thereby forcing the fluid out from the chamber 54through the outlet port "58 as a result of passage afforded by the duct52, as shown in FIG. 6. When the piston traverses .180rotational'dis'placement, the piston will either bottom or stop short ofthe bottom of the cylinder 46 depending At this time, the piston will bedisposedv at the beginning of its retraction stroke at which the outletport 58 is sealed by the piston head and the ducts 52'open the pumpingchamber 54 to the inlet port 56, as'illustrat'ed in FIG. 7. As thepiston 48 is retracted or withdrawn in the cylinder 46, the createdsuction will forcethe pumping fluid into the expanding plumpinglchamber54 through the duct 52 from the inlet port 55, as shown in FIG. 8, untilsuch time as the piston is disposed in the cylinder at the start of thecycle, as represented in FIG. 5. The inlet port 56 will, at this point,be sealed by the piston head; and the pumping chamber 54 will be incommunication with the outlet port 58 by means of the interposed ductSZ.

When the cylinder is pivoted 'in aclockwise direction, as shown in FIG.3 and as represented 'by E1629, the piston 48 will be bottomed or at thebeginning of the suction part of the pumping cycle.' The port 58, undersuch circumstances, will be the inlet port with port 56 serving as thoutlet. At the start of the cycle, the outlet port 56 will be sealed bythe piston head and the inlet port 5% opened to' permit introduction ofthe pumping fluid through the duct 52 into the pumping chamber 54. Asthe piston 48 rotates, it will be retracted, as shown in FIG. 10, suchthat the created suction will force the-pumping fluid into the chamber Sthrough the space afforded by the duct 52; When the piston has rotatedthe inlet port 5 8 will be sealed by the piston head and the outlet port5% opened and the piston will be disposed at the end of its retractionstroke andbeginning of its forwardpumping stroke, as shown'in FIG. 11.Accordingly, the piston willthen be forced inwardly of the cylinder 46whereby the pumping fluid in the chamber 54 will be forced through theduct 54 out through the outlet port 56, a depicted by FIG. 12, until thestart of the cycle is reached at which the disposition of parts is thatillus trated in FIG. 9. With the foregoing in mind, the operation ofthe'several contemplated pumps illustrated in FIGS. 13 to 21 will bereadily apparent. With respect. to the monoplex pumps, typified by FIGS.13, 16 and 19, the changes from pumping to suction phase and fromsuction to pumping phase are not accompanied by valve suck back lossesbecause'of the elimination of check valves. Thus, metering values aremore accurately predictable and reproducible with these units than withvalve type piston metering pumps. These pumps are single acting unitsthat pump with single phase, half sign wave output characteristics.

In FIG. 16, the basic monoplex pump is shown with incorporatedscavenging means '70. In this embodiment, those part corresponding tothose previously discussed will be similarly numbered with accompanyingprimes. In this embodiment, rod and gland scavenging'isfacilitatedwhereby piston and gland bypass iluids can be returned atnegative pressure to the suction side of the fluid system or directly tothe fluid source at atmospheric pressure, thus eliminating gland leakageproblems.

In FIG. 19, a multiple pump unit in monophase relationship'is providedin which the half sign wave out-put characteristics of each aresuperimposed to provide a substantially single phase rectified full Wavefluid output characteristic. In this embodiment of the twin monoplexpump, each pump is arranged to pnovide for uni-directional or reversibleflow. Since the basic pump unit of this embodiment corresponds with thatof FIG. 13, the parts will be similarly numbered. It should beunderstood, as is likewise the case with the other versions of multiplepump to be discussed, that more than two pumps may be employed in aneffort to obtain the desired flow patternand characteristics. Inaddition, suitable means may provide for identical piston stroke andreciprocation or piston reciprocation in a prescribed ratio.

With respect to the double 'monoplex pumps exemplified by FIGS. 14, 17and 20, two separate compatible fluids can be handled simultaneously atproportionate flow rates. These pumps may either have equal chamber andduct capacites at both ends of the rotatable and reciprocal piston orspecified chamber and duct ratios. As is evident, either midchamber orrod end scavenging versions of this pump are possible. a

In the double acting pump of FIG. 14, the cylinder 46:: contains therotatable and reciprocal piston 43a which includes at both of itsinterior ends ducts 52a each of which serve to open and close during thepumping cycle, two pairs of ports 56a and 58a. The clearance providedbetween the end of one duct and the beginning of the next is determinedby the diameter of the opposed ports in the cylinder and is ordinarilythis dimension or larger. The output flow characteristics resembleessentially a single phase rectified full wave. These double actingpumps can obviously be operated at negative pressures for piston packingglands while head pressures are highly positive. This may beaccomplished by operating the packing gland end of the piston as afeeder tor the head pressure end of the piston. By the same expedient,this double acting unit can be used as a blender, drawing from two,separate solution sources simultaneously and discharging themechanically mixed product of the two sources into a single dischargeport.

In the double monoplex scavenger pump of FIG. 17, a scavenging means749a is incorporated at the rod end of the cylinder. The remaining partsor components will find their counterparts in the embodiment of FIG. 14and, for this reason, will be similarly numbered with accompanyingprimes. r

In the twin double monoplex pump of FIG. 20, a rectified multiphase flowtransfer characteristic is provided. As the number of individual pumpunits of this version increases, a broad range of flow characteristicsare possible. Since the individual pumps of this composite unit areessentially the double monoplex pump of FIG. 14, the parts will besimilarly numbered.

Referring now to the duplex pumps illustrated in FIGS. 15, 18 and 21, itshould be initially appreciated that these pumps otter optimum singlepiston pumping characteristics with a two port arrangement. The pumpingefiiciency of this pump is extremely high and, due to the sharp flowcutoff at the end of each half cycle, ripple suppression of both inputand output may be effected through relatively low volume accumulators.These duplex pump units are exceptionally versative and work equallyWell in compressonyalve, flow regulator and pump applications. In thebasic duplex pump of FIG. 15, a cylinder 46b contains the rotatable andreciprocal piston 48b having at both of its interior ends a somewhatelongated duct 52b. The clearance provided between the end of one ductand the beginning of the next is determined by the, diameter of theopposed ports in the cylinder and is ordinarily this dimension orlarger. The chambers at both of the piston ends will alternatively servein a pumping and suction capacity in transferring the pumping fluidbetween the opposed ports 56b and 58b. The flow characteristics of thisversion is essentially single phase rec'- tified full wave.

In the duplex scavenger pump of FIG. 18, a scavenging means 70b isincorporated in the unit at the rod end of the piston. The remainingparts of this pump find their counterpart in the pump of FIG. 15 and,consequently, will be similarly numbered.

The twin duplex pump of FIG. 21 representing one version of a wide rangeof multiple pumps is made up of individual pump units corresponding tothe basic duplex pump of FIG. 15. Accordingly, like parts will besimilarly numbered. These multiple pump units produce a broad range ofrectified multi-phase transfer characteristics.

In the multiple purnps, FIGS. 19, 20 and 21, the individual pumps arepreferably interconnected by means which enable them to pivot acorresponding amount thereby permitting their respective pistons toreciprocate proportionately. Naturally, if desired, this pivotalmovement can be equal or in terms of some prescribed ratio;

In FIGS, 22 and 23, another embodiment of valveless positivedisplacement pump capable of producing reversible as well as steplessvariable flow is disclosed. Accordingly, a cylinder 146 advantageouslycontains a rotatable and reciprocal piston 14%. This piston includes anoutwardly extending piston rod 149'also adaptedto rotate and reciprocatewith respect to the opening 150 in the rear of the cylinder 146. As anexemplary embodiment, the pump 130 serves as a basic duplex pumpcorresponding to that disclosed in FIG. 15. Thus, both ends of thepiston 148 are provided with ducts 152. In lieu of the single cutout forproviding this duct, as suggested in the previous embodiment, a seriesof elongated slots, cutout or recessed portions may be employed. .Inaddition, a combination of an enlarged cutout portion similar to theprevious embodiments together with these slots may be employed, it beingunderstood that this invention contemplates many other configurationsand combinations of ducts for accomplishing the intended objects andpurposes. Both ends of the piston 148 provide with the interior cylinderWalls spaced and distal pumping chambers 154 which are adapted toalternatively communicate with the ports 156 and 158 by means of theducts 152 in generating the intake and output phases of the pumpingcycle.

The terminal end of the piston rod 149 is provided with a laterallyextending arm 157 the end of which conveniently mounts a ball 15h. Thisball is adapted to cooperate with pivotal yoke 166) by riding in acircumferentially extending internally slotted raceway 162. The outerend of the piston rod 149 additionally includes a collar 164 which iscoupled with the output shaft 166 of the motor drive 132. .The couplingof the collar and motor shaft is such as to render the piston rod 149and, consequently, the piston 14% and cylinder 146 coaxially andpermanently aligned with the output shaft. In order to obtainreciprocation of the piston 143 upon rotation of the motor output shaft166, as well as reversibility of fluid flow, the yoke is permittedpivotal movement with respect to the rotational axis. In the exemplaryembodiment, this pivotal movement is about a vertically extending axis.Assuming rotational movement and pivotal displacement of yoke 160 in aclockwise direction, as viewed in FIG. 23, the pumping fluid in the rearchamber 154 will flow through the rear piston ducts 152 out through theport 158. Simultaneously, therewith, the

' front chambers 154 will take in pumping fluid through the front pistonducts to the port 156. When the retraction stroke of the piston 148 hasended and the forward stroke begins, the fluid in the front cylinderchamber will be' pumped out through the port 158 and the rear chamber154 filled with pumping fluid emanating from the port 156. Pivoting ofthe yoke 160 in acounterclockwise direction, as viewed in FIG. 23, willprovide for reversal of fluid flow.

In order to maintain the coaxial relationship of the drive train, aspline connection means 168 is provided between the'collar 164 and motordrive shaft 166. This ,7 spline connecting means 168 may take the formof splines provided in the opposed surfaces of the collar interior andshaft exterior. Thus, the collar is provided with splines 17% whereasthe shaft is provided with the splines 172. The associated splines arethen interconnected with the interposed ball bearings 174. Accordingly,reciprocation of the piston and, consequently, the piston rod 149 willbe taken up at the spline connecting means 168 and the rotationalmovement of the parts still maintained.

It will be readily obvious that the degree of rotation of the yoke 160will determine the piston stroke and, consequently, the pumping rate. Inaddition, the means for obtaining variable degrees of pistonreciprocation, as well as reversibility of flowof this embodiment, can

in FIGS. 13 through 21 as well as others. 1

In actual practice, pumps of this'invention are capable of flow ratesfrom a few cubic centimeters per hour to hundreds of gallons per minute.Pressures attainable vary from inches of water to thousands of poundsper square inch. Component parts of the pumps can be manufactured frommetals, plastics or cermets as well as other materials. 1

Basic simplicity is thusly provided by the pumps of this inventionwithout limiting their versatility and application. These pumps can beemployed for metering small or large fiows in virtually any head tosuction relationship, namely, positive head pressure, negative suctionpressure; zero head to zero suction; negative head, positive suction.

A pump incorporating the teachings of the present invention hasparticular application in the food and medical industries because theyare readily adapted to meter and pump fluids while maintaining purity.Without check valves which clog, causing. cavitation and failure, thepumps can handle blood and other suspensions, as well as slurries andpastes effectively while providing many years of trouble-free service.In a multiple pump unit, one pump can proportion all of the ingredientsof a constant mix or several pumps driven from one motor can vary theproportions of many mixtures while assuring simultaneous injection ofevery ingredient. With infinite turned down ratio, relatively minutequantities of additive such as spices and preservatives can beproportioned into food mixes; thick antibiotics'can be pumped intoampules for the pharmaceutical industry.

These pumps have utility in instrumentation service where metering andpumping of fluids while maintaining product purity is desired ordictated. Small orifice, needle valve openings and other componentssensitive to contamination can be supplied with pure, clean fluids fortheir operation. The variable flow pattern of the pumps is especiallysuited for accurate control of actuator'traveler valve operatorposition. In fluid power systems, the reverse capability to full reverseflow permits forward and backard flow at rates equal to each other.Without check valves which cause cavitation and failure, the pumps areinsensitive to minor grit and other impurities in hydraulic fluids.

The pumps also have application to the chemical, petroleum, marine andgeneral manufacturing industries where metering and pumping of fluidwhile maintaining automatedbakery, the lard, water, spices,preservatives and vitamin concentrates would be automatically added tothe continuous flour mix. Each additive rate would be controlledindependently at a central control panel in precise volumetricrelationship'to product requirement. All pistons and cylinders would behand removable for periodic cleaning and sterilization.

In a chemical processing plant, mechanically coupled pumps of thisinvention could provide, from a single power source, system commandcontrol facility on a positive hydraulic basis in the positioning ofgates, diverters and other such system mechanisms. Other pumps couldmeter additives and trace materials into the main flow. The main fiowcould be precisely moved by slave pumps responding to flow rate andpressuredernands of the command units. Valve clogging slurries andsemi-solids would be handled directly by pumps of this invention withoutdanger of valve failure or centrifugal separation of product. 7

It will be noted that the duct and port relationship herein describedacts in a true shearing manner. Thus, in sewage and waste handlingapplications, pumps of this invention, particularly those equipped withmultiduct .pistons as illustrated in FIGURES 22'and 23, provide uniquefacility for shredding and pulping of fluid-borne solids.

- Provided with sharp duct and port edges of hard material such astungsten carbide, these pumps would reduce suspended solids and wastematerials. such as paper and fabric to predetermined maximum size forprecise chemical treatment and optimum disposal and, at the same time,would perform the essential transfer function Without danger ofclogging.

In a prime mover application, such as a bull doz'er, the engine coulddrive mechanically coupled pumps of this invention to provideindependently controlled motive power, steering, blade adjustment, winchoperation as well as other functions. Obviously, clutches, shafts,valves, brakes, gear changers and other such presently used system partswould be eliminated. less variation of work rates to meet varying loadrequirements would enhance operating control and machine capability. Thepumps could also be applied to com- .pression of gases with particularadvantages in that the power source canbe started againstzero load andthen be brought on to the line after sustaining velocities have beenreached. System back-pressure can be employed to directly servo'pumpingrates precisely to demandrates and since no valves or bypasses areinvolved, power consumption in continuous operation can be dramaticallyreduced. The doubleactingpiston pumps previously described in feederarrangement provide an extra measure of leakage protection throughnegative packing gland pres- I sures in the handling of controlledgases.

purity is desired. The pumps, as stated, are reversible slurries aseasily as clear fluids, and give years of trouble free service. Internalparts can be readily removed for cleaning, ifnecessary. 4

In specific application considerations, the versatility of the pumpsbecome particularly significant. A- typical food application wouldemploy a single electric motor to provide independentlycontrollableinsertion of all required additives in a continuous mix system. Forexample, in an i If it is desired to provide a variable rate of rotationother than some preselected or prescribed value, a potentiometer or thelike control can be employed for varying the motor output. Under suchcircumstances, a gear reduction system need not be employed.

Thus, among others, the aforenoted objects and advantages are mosteffectively attained. Although somewhat preferred embodiments have beendisclosed herein,

itshould be understood that this invention is in no sense limitedthereby and is to 'be determined by the communicable with said portmeans for transferof said,

fluid to andfrom the cylinderydrive means for said .piston having anaxis; means for'permitting said piston to reciprocate in said cylinderwhile rotating, in atimed ,relation; with respect'to said port means;and means for reversing such timed relationship, said reversing means Inaddition, smooth step being operable to reverse the relative angularitybetween said axes to obtain fluid flow reversal.

2. A single valveless, reversible, variable fluid flow, positivedisplacement metering pump comprising in combination: a'cylinder havingport means for pump fluid; a piston in said cylinder; duct means on saidpiston communicable with said port means for transfer of said pump fluidto and from the cylinder; means for coupling said piston to a source ofrotational energy for rotating said piston; means for reciprocating saidpiston while rotating, in a timed relationship with respect to said portmeans to cyclically open and close said port means; means for varying.the extent of relative reciprocation of said piston; means for reversingsaid timed relationship; and scavenging means for removing pump fluidthat escaped between the associated walls of the piston and cylinder,such latter means including a passage in direct communication with theinterior of said cylinder, said passage being adapted to receive theescaping pump fluid upon reciprocation of the piston.

3. A valveless, variable fluid flow, positive displacement pumpcomprising in combination: a cylinder having a pair of ports for pumpfluid; a rotatable and reciprocal piston having opposed ends in saidcylinder adapted to provide with the cylinder interior a pump chamber ateach end thereof, each of which chamber is adapted to vary in size uponreciprocation of said piston; a pair of duct means on said piston, eachof which are in opposed relationship and located at the piston ends,each of said duct means being in communication with one of said portsfor transfer of said fluid to and from the associated chamber; means forpermitting said piston to reciprocate in said cylinder, while rotating,in a predetermined relationship with respect to said ports toalternately communicate each of the duct means with the other of saidports; and means for varying the extent of relative der having an inletand outlet port; a piston reciprocally and rotatably disposed in saidcylinder and being formed with a duct means communicable with each ofsaid ports; drive means adapted to be coupled with a source ofrotational energy for cooperating to rotate said piston in saidcylinder; actuator means for reciprocating said piston upon operation ofsaid drive means whereby fluid is drawn into said cylinder through saidduct means from one of said ports and then out of said cylinder throughsaid duct and out through the other of said ports; fluid flow reversingmeans for reversing such fluid flow by reversing the intake and outputfunctions of said ports; and scavenger means for removing fluid thatescaped between the associated walls of the piston and cylinder,

such latter means including a passage in direct communication with theinterior of said cylinder, said passage being adapted to receive theescaping pump fluid upon reciprocation of the piston.

5. The invention in accordance with claim 4 wherein said cylinder isprovided with at least two pairs of said ports, and said piston isprovided with a corresponding number of duct means each of which beingcooperable in transmitting fluid between the associated pair of ports.

6. The invention in accordance with claim 4 wherein the piston isprovided with another duct means adapted to communicate with said portsfor supplementing the transfer of fluid by the other duct means.

7. A piston for a reversible, variable flow positive displacement pumpcomprising a cylindrically shaped piston body having cylindrical sidewalls and a first and second end, a first duct means formed in said sidewalls at said first end for providing passage of pump fluid, a secondduct means in said side walls at said second end for providing passageof pump liquid, and at least one of said duct means comprising a seriesof spaced and parallel elongatedrecessed portions extending from a pointintermediate the ends of the body to the associated piston end.

- 8. A single valveless positive displacement pump comprising incombination: a cylinder having port means for pump fluid; a pistonreciprocally disposed in said cylinder; duct means on said pistoncommunicable with said port means for transfer of said pump fluid to andfrom the cylinder; means for coupling said piston to a source ofrotational energy; actuator means for reciprocating said piston uponoperation of the source of rotational energy through the coupling meanswhereby fluid is drawn into said cylinder through said duct means andthen out of cylinder through said duct means through said port means ina timed relationship such that said port means is cyclically opened andclosed by said piston, and

scavenger means for removing fluid that escaped between the associatedwalls of the piston and cylinder, such latter means including a passagein direct communication with the interior of said cylinder, said passagebeing adapted to receive the escaping pump fluid upon reciprocation ofthe piston.

9. A valveless pump comprising in combination: a cylinder having aninlet and outlet port; a piston reciprocally and rotatably disposed insaid cylinder and being formed with a duct means communicable with eachof said ports; drive means adapted to be coupled with a source ofrotational energy for cooperating to turn said piston in said cylinder;actuator means for reciprocating said piston upon operation of saiddrive means whereby fluid is drawn into said cylinder through said ductmeans from one of said ports and then out of said cylinder through saidduct means and out through the other of said ports, said actuator meanscomprising pivotal means .for changing the angular relationship betweenthe axis of the piston and said drive means to change the stroke ofthepiston and vary the fluid flow, said pivotal means pivotallysupporting said cylinder such that said cylinder is pivotal about avertical axis, an arm extending laterally from the exterior end of saidpiston, a cylindrical yoke coaxially coupled with the rotational outputof said drive means; and a universal ball and socket joint meanscoupling the terminal end of the arm and the yoke whereby upon pivotalmovement of the cylinder to a position at an angle to the axis of theyoke, the ball of the joint traverses a substantially elliptical path oftravel in a plane normal to the axis of said piston therebyreciprocating said piston while it turns.

10. A valveless pump comprising in combination: a cylinder having aninlet and outlet port; a piston reciprocally and rotatably disposed insaid cylinder and being formed with a duct means communicable with eachof said ports; drive means adapted to be coupled with a source ofrotational energy for cooperating to turn said piston in said cylinder;actuator means for reciprocating said piston upon operation of saiddrive means whereby fluid is drawn into said cylinder through said ductmeans from one of said ports and then out of said cylinder through saidduct means and out through the other of said ports, said actuator meansincluding a pivotal yoke for changing the stroke of the piston andvarying the fluid flow; and coupling means for the piston and drivemeans, said coupling means being operable to maintain the angularrelationship between the axis of the piston and drive means constant,said coupling including a splined connection 'between the exterior ofthe piston and the rotational output of said drive means such thatrelative reciprocation is permitted therebetween While the angularrelationship is maintained therebetween upon pivoting of the yoke means,the splined connection inat an angle less than 90 to the axis of saidpiston, the

ball traverses a substantially elliptical path of travel in meanswhereby fluid is drawn into said cylinder through said duct means fromone of said ports and then out of said cylinder through said duct meansand out through the other of said ports; and scavenger means forremoving fluid from the interior of the cylinder that escapes betweenthe associated walls of the piston and cylinder.

12. A pump comprising in combination: a cylinder having an inlet andoutlet port; a piston reciprocally and rotatably disposed in saidcylinder and being formed with a duct means communicable with each ofsaid ports; drive means adapted to be coupled with a source ofrotational energy for cooperating to rotate said piston in saidcylinder; actuator means for reciprocating said piston upon operation ofsaid drive means whereby fluid is drawn into said cylinder through saidduct means from one e f said ports and then out of said cylinder throughsaid "duct and out through the other of said ports, said actuator meanscomprising pivotal means for changing the angular relationship betweenthe axis of the piston and said drive means, said pivotal meanspivotally supporting said cylinder such that saidcylinder is pivotalabout a vertical axis, an arm extending laterally from the exterior endof said piston, a cylindrical yoke being coaxially coupled with therotational output of said drive means; and a universal ball and socketjoint means -ccu-' pling the terminal end of the arm and the yokewhereby upon pivotal movement of the cylinder to a position at an angleto the axis of the yoke, the ball of the joint traverses a substantiallyelliptical path of travel in a plane normal to the axis of said pistonthereby reciprocating said piston while it rotates; fluid flow reversingmeans for reversing such fluid tlow by reversing the intake and outputfunctions of said ports; and scavenger means for removing fluid thatescaped between the associated walls ot'the piston and cylinder.

13. A pump comprising in combination: a cylinder having an inlet andoutlet port; a piston reciprocally and rotatably disposed in saidcylinder and being .formed with a duct means communicable with each ofsaid ports; drive means adapted to be coupled with a source ofrotational energy for cooperating to rotate said piston in saidcylinder; actuator means for reciprocating said piston upon operation ofsaid .drive means whereby fluid is drawn into said cylinderfthrough'saidductmeans from one of said ports and then out of said cylinder throughsaid duct and out though the other of said ports; coupling means beingprovided for maintaining the angular relationship betweenthe axis of thepiston and drive means and the axis of rotation constant, and a pivotalyoke means for changing the relationship between the duct means and'ports, the coupling means including 'a splined connection between theexterior end of the :piston and the rotational outputof said drive meanssuch that relative reciprocation is permitted and a coaxial relationshipis maintained therebetween, said piston including a laterally extendingarm having a ball hearing at its terminal'end, said yoke means includingan internal raceway in which said ball is adapted to travel, wherebyupon pivotal movement of said yoke means to a position at an angle lessthan to theaxis of said piston, the

ball traverses a substantially elliptical path of travel in a plane atsaid angle to the axis of said piston while said piston rotates; fluidflow reversing means for reversing such fiuid'flow by reversing theintake and output functions of said ports; and scavenger means forremoving'fluid thatescaped between theassociated Walls of the piston andcylinder.

' 1 References Cited by theExaminer UNITED STATES PATENTS LAURENCE V.EFNER, Primary Examiner.

WARREN E. CQLEMAN, Examiner.

1. A SINGLE VALVELESS REVERSIBLE POSITIVE DISPLACEMENT PUMP COMPRISINGIN COMBINATION: A CYLINDER HAVING PORT MEANS FOR PUMP FLUID; A ROTATABLEPISTON IN SAID CYLINDER, SAID PISTON HAVING AN AXIS; DUCT MEANS ON SAIDPISTON COMMUNICABLE WITH SAID PORT MEANS FOR TRANSFER OF SAID FLUID TOAND FROM THE CYLINDER; DRIVE MEANS FOR SAID PISTON HAVING AN AXIS; MEANSFOR PERMITTING SAID PISTON TO RECIPROCATE IN SAID CYLINDER WHILEROTATING, IN A TIMED RELATION WITH RESPECT TO SAID PORT MEANS; AND MEANSFOR REVERSING SUCH TIMED RELATIONSHIP, SAID REVERSING MEANS BEINGOPERABLE TO REVERSE THE RELATIVE ANGULARLY BETWEEN SAID AXES TO OBTAINFLUID FLOW REVERSAL.